Talks to Watch

David Kriesel: Lies, damned lies and scans

58K views · Aug 22, 2015 · 52:59 · 2 HN recommenders · 5 mentions · discussed 2020–2026

David Kriesel's FrOSCon talk on how Xerox scancopiers, due to JBIG2 compression, silently replaced digits in scanned documents. He walks through how he discovered the bug and why it is so dangerous.

Why Hacker News points people here: The standard reference whenever HN discusses the Xerox scanner bug or AI and compression that fabricates content.

“There a few videos of David Kriesel explaining the bug for the curious”HN comment, 2020

What Hacker News said 5

RecommendsbXVsbGVyAug 2020

“There a few videos of David Kriesel explaining the bug for the curious”

Explains the Xerox scanner compression bug that altered digits in scans.

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> You may remember that this played a strange role in Obama's birth certificate some years back Just to clarify, the issue with the compression algorithm used by the scanner, not with the PDF format itself. There a few videos of David Kriesel explaining the bug for the curious: this video

in “PDF: Still unfit for human consumption, 20 years later” · view on HN
Recommendslynx23Jun 2023

“the CCC had a pretty neat presentation at that time as well”

A neat CCC presentation about the Xerox document-altering scanner bug.

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Even though this happened a long time ago, whenever I hear or think about it, I am a mazed that it didn't put Xerox out of business, or at least hurt a little more. After all, some big players were already doing digital archiving at the time. :-/ BTW, the CCC had a pretty neat presentation at that time as well: this video

Cites itdorgoMar 2021

“Xerox scancopiers literally are making stuff up”

Describes Xerox scanners silently replacing digits in scanned documents.

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Sounds like the next iteration of "Lies, damned lies and scans": this video >On the scale of things too horrible to contemplate, "document-altering scanner" is right up there with "flesh-eating bacteria". Since 2006, Xerox scancopiers literally are making stuff up. They, for example, replace digits with others in scans.

in “Adobe Photoshop's 'super resolution' made my jaw hit the floor” · view on HN
Cites itmaxnoeNov 2021

“And the talk he gave in English himself here”

English-language version of the talk on the Xerox scanning bug.

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There is a version with an English voice over of the original talk here: link And the talk he gave in English himself here: this video

in “Confused Xerox copiers rewrite scanned documents, expert finds (2013)” · view on HN
Cites itTerr_Mar 2026

“I'm reminded of the Xerox JBIG2 bug back in ~2013”

Covers the JBIG2 scanner bug that silently replaced numbers in documents.

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> OCR for construction documents does not work I'm reminded of the Xerox JBIG2 bug back in ~2013, where certain scan settings could silently replace numbers inside documents, and bad construction-plans were one of the cases that led to it being discovered. [0] It wasn't overt OCR per se , users weren't trying to convert pixels to characters. [0] this video

in “OCR For construction documents does not work, we fixed it” · view on HN